correct spelling mistake

src/util/distance-iterator.js

@@ -39,7 +39,7 @@ export default function(start, minLine, maxLine) {
  return iterator();
  }
 
- // We tried to fit hunk before text beginning and beyond text lenght, then
+ // We tried to fit hunk before text beginning and beyond text length, then
  // hunk can't fit on the text. Return undefined
  };
 }